Device for compacting and draining fluid sludges containing fibrous materials

Abstract

Device for compacting fluid sludges containing fibrous materials, consisting in slowly stirring the sludge mechanically in the top part of a device, then pressing it moderately in a conical intermediate part of the device and then compacting it in a bottom cylindrical chamber of the device.

What we claim is: 
     
       1. A device for compacting or settling aqueous sludge containing finely divided mineral and fibrous substances of organic or mineral origin after previous treatment by primary and secondary floculation of the sludge in its original liquid support, said apparatus comprising a vertical vessel including an upper cylindrical portion and a lower conical portion, a supply pipe for the sludge to be treated extending tangentially at a level below the top of the cylindrical portion of said vessel, a plurality of rotating perforated blades having a vertical axis installed in said cylindrical portion below said supply pipe, a conical rotating screw having a vertical axis installed in the conical portion of said vessel, said conical screw comprising means including at least one blade having a pitch correlated to the fibrous sludge to be treated so that compressed sludge at this level is not solidified and still contains interstitial water, said conical portion having a lower end with an outlet orifice thereat for compressed sludge, a spillway at the upper end of the cylindrical portion of said vessel for the discharge of a part of the interstitial water contained in the sludge, a horizontal cylindrical chamber secured to said conical portion of said vessel at the outlet orifice, said chamber including a downstream portion having a wall constituted as a grating for the discharge of remaining interstitial water contained in the sludge, a rotating screw installed in said chamber and extending beneath said outlet orifice, said chamber having an outlet orifice at an end thereof for discharge of compacted sludge, and flexible outlet means at said orifice having a conical shape and a free end with an outlet diameter which is smaller than its inlet diameter. 
     
     
       2. A device according to claim 1, wherein the conical screw has perforations. 
     
     
       3. A device according to claim 1, wherein the grating of said cylindrical chamber has a cylindrical shape. 
     
     
       4. A device according to claim 1, wherein said flexible outlet means has a varying thickness and is thicker near its base and thinner near its outlet. 
     
     
       5. A device according to claim 1, wherein the grating of the cylindrical chamber is of wire gauze type. 
     
     
       6. A device according to claim 1, wherein the grating of the cylindrical chamber has slots. 
     
     
       7. A device according to claim 6, wherein the slots are in the shape of shells opening outwards. 
     
     
       8. A device according to claim 1 comprising fixed blades disposed on the inside wall of the grating. 
     
     
       9. A device according to claim 8, wherein the fixed blades are parallel to the axis of the pressing rotating screw in the cylindrical chamber. 
     
     
       10. A device according to claim 8, wherein the fixed blades wind inside the cylindrical chamber at a predetermined pitch. 
     
     
       11. A device according to claim 1, wherein the grating is constituted by bars having a trapezoidal cross-section, the largest width of the bars being inside the chamber, these bars being parallel to the screw in the chamber and longitudinal alveoli closed by strips being formed between certain bars. 
     
     
       12. A device according to claim 1, wherein the grating of said cylindrical chamber has a cylindrical portion and a terminal conical portion.